From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparison of power output between Aerolite and EB.1299 pistons for Bentley engines.
| Identifier | ExFiles\Box 87\2\ scan0131 | |
| Date | 10th February 1936 | |
| x236 Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews}1/KW.10.2.36. Bentley Pistons. With regard to Aerolite pistons, these were standardised on account of their low power loss due to friction. At the same time it must be taken into account that they were better pistons for mechanical strength than the EB.1299; they had not perhaps quite the same margin of safety for piston knocks but there have been remarkably few complaints of knocks since they were fitted. Our first tests showed that the Aerolite piston was definitely better than the EB.1299 piston for power output, being approximately 7% to 8% better than the standard at that time. We have taken an average of 12 production engines having EB.1299 pistons and 12 engines having Aerolite pistons, and these figures show that the Aerolite piston is definitely better at low speeds, although they do not appear to be much better than EB.1299 at the high speeds. We should prefer to take the readings at high speed with open exhaust and the air silencer removed, but even taking the results with both air and exhaust silencers fitted, there is an appreciable gain at low speed as shown below :- | R.P.M. | Increase in power by using Aerolite pistons against EB.1299. Figures taken from an average of 24 production engines with EB.1299 and Aerolite Pistons | |---|---| | 750 | 8.5% | | 1000 | 8.3% | | 1500 | 8.0% | | 2000 | 6.2% | | 2500 | 5.0% | | 3000 | 4.0% | | 3500 | 3.0% | | 4000 | 1.3% | | 4250 | 1.0% | | ||